
In this equation \(\pi _{ab}\)  is called "squared" energy momentum tensor; which contains quadratic combinations of \(T_{ab}\) (for explicit expressions see[1]}, [2]}). If a Maxwell field is confined on the brane, then \(T_{ab}\)  is given by[3]}, [4]}, [5]},
\(T_{ab}=\frac{1}{4\pi }\left(F_{ac}F^{c}_{b}-\frac{1}{4}h_{ab}F_{cd}F^{cd}\right)~,\) 
